Metering cabinet is an essential component of switchgear, used to measure and monitor various electrical parameters, such as voltage, current, power, energy, and frequency, in power distribution systems.
Our metering cabinet is designed to meet the industry’s highest standards for accuracy, reliability, and safety. It comes with advanced features, such as digital display, data logging, communication interfaces, and protective functions, to provide real-time information and control over the electrical network.
Note: The above parameters are for reference only and are subject to change without notice.
FAQ Guide
The power supply system, as an indispensable infrastructure for modern urban life, carries the important mission of safely and stably delivering high-voltage electric energy to thousands of households. Through ingenious engineering design and precise equipment configuration, this system realizes multiple functions such as voltage reduction, protection, metering, and distribution of electric energy, providing users with reliable and efficient power services. This article organizes the frequently received questions into a text to explain in detail the meaning and function of components such as metering cabinets and PT cabinets in high and low-voltage cabinets.
1. What are high and low-voltage cabinets?
High and low-voltage cabinets are key equipment in the power system, used for power transmission, distribution, and control. According to the purpose, there are incoming line, outgoing line, metering, PT, and capacitor cabinets; according to the structure, there are fixed type and trolley type; according to the function, there are switches, protection, and control cabinets. It is necessary to select the appropriate type according to the specific scenario and needs to ensure the safe, stable, and efficient operation of the power system. With the development of power technology, high and low-voltage cabinets are constantly updated and improved to provide support for the development of the power system.
2. What is the working principle and composition of high and low-voltage cabinets?
As the name implies, high and low-voltage distribution cabinets are distribution equipment used for power distribution, control, metering, and cable connection in the power supply system. Switch cabinets are generally used in power supply bureaus and substations in conjunction with transformers to step down power to the low-voltage distribution cabinet.
Low voltage distribution cabinets are used in distribution boards, control boxes, and switch boxes for various power consumption. They are equipment for distribution devices that meet the design functional requirements by assembling some switches, circuit breakers, fuses, buttons, indicator lights, meters, wires, and other protective devices into one. Commonly known as high and low-voltage switch cabinets or high and low-voltage electrical complete sets of equipment.
High-voltage incoming line cabinet, metering cabinet, high-voltage outgoing line cabinet, low-voltage incoming line cabinet, capacitor cabinet, and low-voltage outgoing line cabinet are the regular configurations of the distribution room. Regardless of high or low voltage, they are combined together according to certain functions.
High-voltage incoming line cabinet: A switch cabinet that introduces power from the outside. Generally, it introduces 10kV power from the power supply network and sends the power to the 10kV busbar through the switch cabinet. It is a high-voltage cabinet that disconnects the high-voltage incoming line power supply. In fact, it is not a real incoming line cabinet. The incoming line is connected to the isolation cabinet, but it has a circuit breaker (vacuum) that can disconnect the incoming line power supply, so it is called an incoming line cabinet.
Metering cabinet: A cabinet specially installed with metering devices to accurately measure how much electricity you use. This cabinet has no other major components except PT (voltage transformer) and CT (current transformer).
High-voltage distribution cabinet: Its function is to distribute and transmit electrical energy. It usually carries a transformer or high-voltage electrical equipment (motor) and high-voltage compensation equipment.
Low-voltage incoming line cabinet: It is usually the first cabinet coming down from the transformer, also called the low main cabinet, which is used to control all the electrical equipment below. Its main switch generally uses a frame circuit breaker.
Capacitor cabinet: Its function is to compensate for the quality of electricity consumption and improve the power factor!
Low-voltage distribution cabinet: Its function is to distribute and transmit electrical energy. Unlike a high-voltage distribution cabinet, it basically directly reaches the electrical equipment, and the switch generally uses a molded case circuit breaker.
3. What is the specific meaning of a metering cabinet?
The main components of the metering cabinet are the current transformer, fuse, voltage transformer, and live display.
The meter cabinet is a type of electric energy metering device. It uses a high supply and high metering method to measure the power consumption of the load through current transformers, voltage transformers, electric energy meters, and other metering devices and reflect the power consumption of the load. As an electric energy metering device, it is used to measure and record electric energy consumption, which is of great significance for taking energy-saving measures and optimizing electricity use.
Metering cabinets include fixed electric energy metering cabinets and removable electric energy metering cabinets, which are divided into dedicated high-voltage electric energy metering cabinets and dedicated low-voltage electric energy metering cabinets. They are suitable for different scenarios and business needs.
4. What is the specific meaning of a PT cabinet?
The main components of the PT cabinet are a voltage transformer, isolating knife, fuse, and lightning arrester. It has the following functions:
Voltage measurement, providing voltage circuit for measuring meter;
Can provide operation box operation power supply;
Installation of overvoltage protector for each bus section;
Relay protection requirements, such as busbar insulation, overvoltage, undervoltage, and backup automatic switching conditions.
5. What is the difference between a PT cabinet and a metering cabinet?
PT cabinets have handcarts. The measuring cabinets are divided by regions, and some areas do not have handcarts, while others do.
The PT cabinet has a lightning arrester, which is placed in the trolley or behind the cabinet. The metering cabinet does not have a lightning arrester.
The PT cabinet has no live display, but the metering cabinet has a live display.
PT does not have a current transformer, but the metering cabinet does.
The metering cabinet is usually used as a metering outgoing cabinet or a metering connection cabinet. The PT cabinet is usually behind the incoming cabinet and before the feeder cabinet. Only the main busbar passes through it, and it is not used for outgoing lines.
6. How do you choose a metering device?
In high-voltage and low-voltage distribution cabinets, the selection and installation of electric energy metering devices are crucial. I will explain them separately below.
1). Functional requirement analysis
First, the requirements need to be clarified, such as whether it is necessary to support multiple measurement points, communication functions, data collection frequency, etc.
2). Measurement accuracy
Choose an electric energy metering device with higher accuracy. Generally, the accuracy level of the electric energy metering device should be consistent with the national standard requirements to ensure that the accuracy meets the requirements.
3). Security considerations
When choosing an energy metering device, its safety performance should be considered. Make sure the device has safety protection functions such as overvoltage, overcurrent, and overtemperature to prevent power accidents.
4). Communication interface requirements
If necessary, select an energy metering device with a communication interface to achieve remote data monitoring and management. Common communication interfaces include RS485, Modbus, Ethernet, etc. Select the appropriate communication interface type according to actual conditions.
5). Comprehensive cost considerations
During the selection process, it is necessary to comprehensively consider factors such as the performance, price, and maintenance cost of the device and select an electricity metering device with a higher cost-effectiveness.
7. How to install a metering device?
Then we will introduce how to install a metering device.
1). Installation location selection
The installation location of the electric energy metering device should be selected at the terminal of the power supply system to ensure the accuracy of the measurement. At the same time, it should be away from strong electromagnetic fields and other interference sources to avoid affecting the device. It is also necessary to ensure that there is enough operating space around the distribution cabinet for maintenance and repair.
2). Installation environment requirements
When installing the electric energy metering device of the high-voltage and low-voltage distribution cabinet, ensure that the environment is dry, well ventilated, the temperature is appropriate, and avoid the influence of dust, moisture, etc. on the device.
3). Wiring and connection
Pay attention to grounding protection during installation. The metal shell and metal parts of the distribution cabinet should be reliably grounded to ensure personal safety and normal operation of the equipment. During the grounding process, pay attention to the requirements of grounding resistance to ensure the reliability of the grounding system. Connect according to the wiring diagram of the electric energy metering device and ensure that the connection is reliable and firm. Be careful to avoid wiring that is too long or too short and avoid overly complicated lines. Wiring and connection should be carried out in accordance with relevant standards.
4). Withstand voltage test
After the installation is completed, the function test and safety inspection of the power distribution cabinet should be carried out to ensure that the equipment meets the requirements and can operate normally. At the same time, the insulation test and grounding test of the power distribution cabinet is also required to ensure the safety and reliability of the equipment, determine that the insulation performance of the electric energy metering device meets the requirements, and avoid the occurrence of leakage accidents.
5). Calibration and debugging
After the installation is completed, the electric energy metering device should be calibrated and debugged. According to the operating instructions provided by the manufacturer, the calibration and debugging should be carried out according to the corresponding process to ensure the normal operation of the device.
8. How to maintain and repair metering devices?
Inspection and maintenance work should include, but not be limited to, the following:
Newly powered switchgear should be inspected once during one month of operation, and all busbar connection fasteners should be retightened.
Perform measurement tests regularly to ensure the accuracy of the test results.
The environment with dust and fiber should be inspected and maintained regularly. The switch cabinet should be inspected, cleaned, and maintained at least once a month.
Daily inspection and maintenance work should comply with the relevant regulations of the power supply department.
When a switch cabinet failure is found, it should be repaired immediately. For operation and maintenance, please refer to the relevant instructions and samples.
Repair work should be done by professionals who are familiar with the equipment and hold an electrician’s license. Relevant safety regulations must be strictly followed, or professionals from the power supply department or the manufacturer’s after-sales service personnel should be hired to do the repair.
9. Conclusion
High and low-voltage electrical cabinets are important components of the power system, and the selection and installation of electric energy metering devices are also important links to ensure accuracy and safety. It is also worth noting that power safety should be carried out throughout, not only during selection, installation, and commissioning but also during regular maintenance and inspection.
